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Thursday, November 29, 2007

The occurrence of lightning in a planetary atmosphere enables chemical processes to take place that would not occur under standard temperatures and pressures. Although much evidence has been reported for lightning on Venus, some searches have been negative and the existence of lightning has remained controversial. A definitive detection would be the confirmation of electromagnetic, whistler-mode waves propagating from the atmosphere to the ionosphere.

Here we report observations of Venus' ionosphere that reveal strong, circularly polarized, electromagnetic waves with frequencies near 100 Hz. The waves appear as bursts of radiation lasting 0.25 to 0.5 seconds, and have the expected properties of whistler-mode signals generated by lightning discharges in Venus' clouds.

Sunday, November 18, 2007

Homo sapiens is the only existing primate species lacking in functionally effective thermally insulating fur. As all other primates have considerable hair covering, it has always been accepted that our ancestors must once have had a respectable amount of body hair. Unfortunately, fossils cannot help us when it comes to differences in skin and hair. Recent DNA analysis, however, has given us some idea of when and where the great denudation took place.

A number of hypotheses have been proposed to account for this feature, but none of these has gained general acceptance. All will be explained here.

Saturday, November 10, 2007

In this day in 1885, the world's first motorcycle, designed by Gottlieb Daimler, made its debut. The frame and wheels were made of wood. A leather belt transfered power from the engine to large brass gears mounted to the rear wheel. The leather saddle wasn't very comfortable since there was no suspension (front or rear). The single cylinder engine had a bore of 58mm and stroke of 100mm giving a displacement of 264cc's. The engine gave 0.5hp at 700 rpm. The top speed for the motorcycle was 12 km/h. This was built as an experimental vehicle to test the new Daimler engine, which was to power Daimler's first motorized carriage the following year.

Friday, November 9, 2007

On this day in 1957, Gordon Gould began to write down the principles of what he called a laser in his notebook during a sleepless Saturday night. By Wednesday morning he had a notary witness and date his notebook. Therein, he had described what he called "light amplification by stimulated emission of radiation," or, from those initials, "laser."

Unfortunately, he misunderstood the patent process, and did not file promptly. But, other scientists, Charles Townes and Arthur Schawlow, did file for a patent on their similar but independent discovery of how to make a laser. When Gould belatedly tried to get a patent, it took decades to eventually establish priority and gain what had then grown to be profitable royalties from the established laser industry.

On this day in 1961, the X-15 rocket plane achieved a world record speed of 4,093 mph (Mach 6.04) and reached 101,600 feet (30,970 m or over 19 miles) altitude, piloted by U.S.Air Force Major Robert M. White. Its internal structure of titanium was covered with a skin of Inconel X, a chrome-nickel alloy. To save fuel, the X-15 was air launched from a B-52 aircraft at about 45,000 ft.

Test flights between 8 Jun 1959 and 24 Oct 1968 provided data on hypersonic air flow, aerodynamic heating, control at hypersonic speeds and piloting techniques for reentry used in the development of the Mercury, Gemini, and Apollo spaceflight programs. The X-15 reached 354,200 feet (107,960 m, 67 miles) on 22 Aug 1963 and Mach 6.7 on 3 Oct 1967.